(1) Field of the Invention
This invention relates to agricultural planters to drop seed and more particularly to a vacuum single seed precision planter.
(2) Description of the Prior Art
There have recently been developed single seed planters using a vacuum to hold single seed to a perforated disc. GUGENHAM, U.S. Pat. No. 3,990,606 issued Nov. 9, 1976, shows such a system.
These systems include a perforated plate or disc which separates a seed reservoir from a vacuum chamber. Differential pressure hold the seed from the seed reservoir to the disc. As the disc is rotated it brings the seed to a release mechanism. The release mechanism may be either an interupter or an ejector. Normally, an interupter will interupt the vacuum upon the perforation and, therefore, permit the seed to drop because there is no vacuum. An ejector is similar to a scraper which ejects the seed by scraping it off the plate.
Vacuum planters have a definite limitation as to the number of seeds which can be dropped for a unit time. This limit is imposed by the number of holes or perforations which can be placed in the plate and the linear speed at which the plate can be moved through the reservoir of seed. Since there is this limitation on the number of seeds that can be dropped, this limits a top speed of the planter to plant the seed at the desired plant density.
It has been suggested that a solution to this problem is that the seed be held by differential air pressure upon the peripheral face of a drum rather than upon a radial face of the disc. Then, more than one row of the seed may be held to the drum. ENEBECK, U.S. Pat. No. 2,505,758, discloses such an arrangement. Other workers in the field, such as PARKS, JR. U.S. Pat. No. 4,148,414, and BAUMAN ET AL. U.S. Pat. No. 3,762,603, have used such a drum with a series of perforations therein with each perforation being used with a separate discharge chute.
Before this application was filed applicant was also aware of the following U.S. Pat. Nos.:
LAMAZOU ET AL.--2,991,909; PA1 WINTER--3,142,274; PA1 STERLING--3,209,888; PA1 LOESCH ET AL.--3,637,108; PA1 ZAGOTTA ET AL.--3,680,737; PA1 BEEBE--3,788,518.